Descriptions

Macromoth diversity, abundance, and community structure in the topographically complex
HJ Andrews Experimental Forest and LTER site was studied on the west slope of the Cascade Range,
Oregon. Data on 493 macromoth species (62,221 individuals) was sampled eight times/year at 20 locations
from 2004 to 2008 and examined using multivariate statistics and generalized additive models to determine
the importance of topography and vegetation on moth community assembly and diversity. Significant
differences exist between moth communities at lower and higher elevations. High-elevation moth
communities are far more variable inter-annually, whether associated with high-elevation forests,
meadows, or clearcuts. Low-elevation young and old gymnosperm forests and riparian forests are more
stable and predictable communities having less inter-annual variability. High-elevation communities show
more intra-annual variability than low-elevation communities. Low-elevation moth communities are more
abundant than high-elevation communities and typically associated with the most common, abundant
species of macromoths in the study. High-elevation communities, by contrast, are associated with less
abundant, more evenly distributed species, as well as with rare moth species. Macromoth community
structure and diversity were related to year or sample period and structural descriptions of vegetation
communities, but not related to known host-plant diversity. High-elevation communities are threatened by
contraction of montane meadows and climate change which, given the variability in high-elevation
communities, could severely impact the biological diversity of the western Cascades landscape. Nocturnal
macromoths represent an important potential indicator of ecosystem health and change.